Silicon-containing films are used for a wide variety of applications in the semiconductor industry. Silicon-containing films include silicon films such as epitaxial silicon, polycrystalline silicon (poly-Si), and amorphous silicon, epitaxial silicon germanium (SiGe), silicon germanium carbide (SiGeC), silicon carbide (SiC), silicon nitride (SiN), silicon carbonitride (SiCN), and silicon carboxide (SiCO). As circuit geometries shrink to ever smaller feature sizes, lower deposition temperatures for Si-containing films may be preferred, for example because of introduction of new materials into semiconductor devices and reduction of thermal budgets of shallow implants in source and drain regions. It is also evident that non-selective (blanket) and selective deposition of Si-containing films will be needed for future devices.
Epitaxial deposition is a process where the crystal lattice of the bulk substrate is extended through deposition of a new film that may have a different doping level than the bulk. Accordingly, a surface of a single crystal Si (SiGe) substrate or film is required for depositing an epitaxial Si (SiGe) film thereon. Prior to depositing a Si-containing film on a substrate, for example epitaxial Si or epitaxial SiGe films, it may be required to remove a native oxide layer from the surface of the substrate in order to prepare a proper starting growth surface (i.e., a seed layer) to deposit a high quality epitaxial film. Moreover in epitaxial deposition, matching target epitaxial film thickness and resistivity parameters are important for the subsequent fabrication of properly functioning devices.
Silane (SiH4) is commonly used for depositing Si and other Si-containing films. However, substrate temperatures greater than about 700° C. are often needed for achieving deposition rates that are suitable for manufacturing of integrated circuits. Thus, use of silane is undesirable in processes having a low thermal budget. Co-pending U.S. patent application Ser. No. 10/673,375 suggests using chlorinated silane gases to increase deposition rates and, therefore, reduce required deposition temperatures.